The invention is directed to a method and apparatus for high data rate wireless communications over wavefield spaces. In particular, the invention provides a high data rate wireless communication between transceivers using a multi-dimensional technique.
The wireless communication industry is responding to consumer demand for high speed data services. The increased Radio Frequency (RF) spectrum acquisition costs associated with the achievement of throughputs that are comparable with wired communication technology has dramatically enhanced the interest in new methods to obtain spectrally efficient modulation formats. The technical challenge posed by these emerging requirements is residing in the intrinsic physical limitations of the wireless propagation environment. Noise, interference, severe multipath and time-varying characteristics of the fading channel contribute to make high-speed wireless data communications a difficult and challenging problem. Traditional communication engineering theory states that an increase in data rate is achieved by a combination of an increase in bandwidth occupation, an increase in radiated power at the transmitter, and an increase in dimensionality in the signal space (that is the order of the digital modulation). A greater description of the prior art and background is provided in Appendix 1 of Provisional Application No. 60/136,699, filed on May 28, 1999 incorporated herein by reference.
Conventional communication technology is depicted in FIGS. 1A-B. A communication network between transceiver A and transceiver B employs a two-dimensional communication protocol using time and frequency. The message to be communicated is broken into a plurality of smaller messages, or packets, that can be sent in the various time slots and frequency slots, according to the communication protocol. Since the receiver knows the communication protocol, it can reassemble the packets to replicate the original message. This type of communication protocol is well known in the art. A greater description of the prior art and background is provided in Appendix 1 of Provisional Application No. 60/136,699, filed on May 28, 1999 incorporated herein by reference.
What is needed is a communication system that provides high data rate communication in a wireless environment. The present invention analyzes practical methods to demodulate high data rate signals transmitted from different positions (antenna elements), that are afflicted by arbitrarily time-varying fading characteristics, with arbitrary time dispersion (frequency selective fading). This is of significant practical interest because in practice the fading environment can never be considered perfectly static even if transmitter and receiver are not in relative motion. The presented method and apparatus do not need training sequences or signals to estimate the channel: this gives additional advantage in terms of throughput with respect to prior art. The method and apparatus is implemented using available hardware for digital radio transceivers.
The invention overcomes the conventional limitations and provides a high data rate wireless communication system between transceivers using a multi-dimensional technique. An exemplary embodiment of the invention for communicating information from one location to another through a wavefield space using a multi-dimensional communication protocol comprises a transmitter configured to receive a message and to encode a plurality of signals associated with the message. A first plurality of antennas is coupled to the transmitter and configured to transmit the plurality of signals associated with the message into the wavefield space. A second plurality of antennas is configured to receive the plurality of signals associated with the message. A receiver is coupled to the second plurality of antennas and configured to decode the plurality of signals associated with the message, wherein the receiver has no advance knowledge of at least one of the dimensions of the multi-dimensional protocol. The receiver reconstructs the message to retrieve the original information.
In one aspect of this embodiment, the multi-dimensional protocol is at least a three-dimensional protocol and the transmitter includes a plurality of transmit modules that each encode at least a portion of the message. The receiver includes a plurality of receiver modules that each decode complementary portions of the message to reconstruct the original information.
In another embodiment, the receiver is configured to execute a statistical procedure to identify and decode the plurality of signals. In one aspect of this embodiment, the receiver is configured to execute a Generalized Likelihood Detection (GLD) procedure to identify the plurality of signals and then execute a Maximum Likelihood Detection procedure (MLD) to decode the plurality of signals. In another aspect of this embodiment, the receiver is configured to estimate the wavefield space using a virtual wavefield space that approximates the wavefield space.
In yet another embodiment of a digital wireless transceiver, the transceiver comprises a digital circuit for detection of U number of different signals after radio frequency intermediate frequency downconversion comprised of digital baseband downconversion, trellis search processor, vector symbol synchronizer, wavefield estimator, wavefield gradient-based estimator, deinterlever, channel decoder and data extractor; and a digital circuit for detection of U number of different signals after radio frequency intermediate frequency downconversion able to cope with and exploit frequency selective multipath propagation, arbitrarily time-varying fading characteristics, non Line-Of-Sight communication.
Advantages of the invention include the ability to communicate high data rates from one location to another, where the data rates are in excess of those conventionally achievable.